A white person. It is spelled Caucasian, because it means from the Caucasus. Are white people from the Caucasus? Unless they are of Georgian, Azerbaijani or Armenian ancestry, probably not. Nevertheless that is what most people mean by the word.
yes
She is African American and all of the other first ladies were caucation.
yes syria is filled with white people. Yes, Syrians are caucation as much as Romans or Greeks are. Syria was part of the Roman empire and a main city for Romans, their capital was Antioch.
Caucasian and Caucasoid are proper terms for "white" people.Aryan (an old-fashioned linguistic term that properly refers to speakers of Indo-European languages) is often used by alleged white supremacists.